React Multi-Context

Manage multiple contexts with a single React component.

Install

• npm install react-multi-context --save or
• yarn add react-multi-context

Test

• npm run test or
• yarn test

Use

import createMultiContext from 'react-multi-context';
export const MyMultiContext = createMultiContext();

Create the context by importing and executing createMultiContext wherever you want to create context. Then, import that multi-context instance as needed.

Use the set prop to set a context's value. Changing the value on a key-value pair in a context will cause all getters for that key to re-render.

Use the get prop to get a context's value. Using this prop will execute the children render prop by passing the corresponding values of the context as the parameters.

Example

// Parent.js
import createMultiContext from 'react-multi-context';

// Context to provide to children.
export const ParentContext = createMultiContext();

export default class Parent extends React.Component {
  render() {
    return (
      <ParentContext
        set={{
          cost: 10,
          project: {
            name: 'React Multi-Context',
            version: 1.0
          },
          user: 'Charles'
        }}
      >
        <Child />
      </ParentContext>
    );
  }
}

// Child.js
// Get the context provided from the parent
import { ParentContext } from './Parent';

export default class Child extends React.Component {
  render() {
    return (
      <ParentContext get={[ 'project', 'user' ]}>
        {(project, user) =>

          /* This is a demo of React Multi-Context v1.0 by Charles! */
          <p>This is a demo of {project.name} v{project.version} by {user}!</p>
        }
      </ParentContext>
    );
  }
}

Example (Shorter)

// Parent - writes A and B
const Parent = () =>
  <MultiContextInstance set={{ a: 1, b: 2 }}>
    <Child1 />
    <Child2 />
    <Child3 />
  </MultiContextInstance>;

// Child1 - reads A
// Note: Each value is its own context, which is what makes this MULTI-context.
const Child1 = () =>
  <MultiContextInstance get={[ 'a' ]}>
    {(a) => `The value of A is ${a}!`}
  </MultiContextInstance>;

// Child2 - reads A and B
// Note: Reading multiple values will trigger a re-render if any one read value changes.
const Child2 = () =>
  <MultiContextInstance get={[ 'a', 'b' ]}>
    {(a, b) => `The value of A+B is ${a + b}!`}
  </MultiContextInstance>;

// Child3 - reads B and A
// Note: The order of the get prop corresponds to the order of the function parameters.
const Child3 = () =>
  <MultiContextInstance get={[ 'b', 'a' ]}>
    {(b, a) => `The value of A+B is ${a + b}!`}
  </MultiContextInstance>;

Default Values

You may pass an object of default values for the contexts as a parameter to createMultiContext or via the default prop.

const MyMultiContext = createMultiContext({ a: 0, b: 0 });

or

<MyMultiContext
  default={{ a: 0, b: 0 }}
  set={{ a: 1 }}
>
  <MyMultiContext get={[ 'b' ]}>
    {b => 'I predict that B equals zero: ' + b}
  </MyMultiContext>
</MyMultiContext>

You do not need to do both.

MultiContext.with

MultiContextInstance.with(...multiContextKeys)(Component) will bind the multiContextKeys of MultiContextInstance to the props of Component.

import React from 'react';
import { SomeMultiContext } from './some-component';

class MyComponent extends React.PureComponent {
  render() {
    return <div children={'My name is ' + this.props.name + ', and I am ' + this.props.age + '!'} />;
  }
}

// Binds the MultiContext's `name` property to MyComponent's `name` prop.
export default SomeMultiContext.with('name', 'age')(MyComponent);

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